Editing Calculator (section)

==Design==
[[File:CalculatorFractions-5550x.jpg|thumb|Scientific calculator displays of fractions and decimal equivalents]]

===Input===
[[Electronics|Electronic]] calculators contain a [[Computer keyboard|keyboard]] with [[Push-button|buttons]] for [[Numerical digit|digit]]s and [[arithmetic]]al operations; some even contain "00" and "000" buttons to make larger or smaller [[number]]s easier to enter. Most basic calculators assign only one digit or operation on each button; however, in more specific calculators, a button can perform multi-function working with [[key combination]]s.

===Display output===
Calculators usually have [[liquid-crystal display]]s (LCD) as output in place of historical [[light-emitting diode]] (LED) displays and [[vacuum fluorescent display]]s (VFD); details are provided in the section ''[[#Technical improvements|Technical improvements]]''.

Large-sized [[Number|figures]] are often used to improve readability; while using [[decimal separator]] (usually a point rather than a [[comma]]) instead of or in addition to [[vulgar fraction]]s. Various symbols for [[Command (computing)|function commands]] may also be shown on the display. [[Fractions]] such as {{math|{{frac|1|3}}}} are displayed as decimal [[approximation]]s, for example rounded to {{math|0.33333333}}. Also, some fractions (such as {{math|{{frac|1|7}}}}, which is {{math|0.14285714285714}}; to 14 [[significant figures]]) can be difficult to recognize in [[decimal]] form; as a result, many [[Scientific calculator|scientific]] calculators are able to work in vulgar fractions or [[mixed number]]s.

===Memory===
Calculators also have the ability to save numbers into [[computer memory]]. Basic calculators usually store only one number at a time; more specific types are able to store many numbers represented in [[variable (mathematics)|variable]]s. Usually these variables are named ans or ans(0).<ref>[https://education.ti.com/en/guidebook/details/en/706B2B75F7D3464EBE6A8F8BE9F00EAC/30xii Texas Instruments TI-30X IIB Quick Reference Guide], Page 1 - Last Answer</ref> The variables can also be used for constructing [[formula]]s. Some models have the ability to extend [[Computer memory|memory]] capacity to store more numbers; the extended [[memory address]] is termed an [[array data structure|array]] index.

===Power source===
Power sources of calculators are [[electric battery|batteries]], [[solar cell]]s or [[mains electricity]] (for old models), turning on with a [[switch]] or button. Some models even have no turn-off button but they provide some way to put off (for example, leaving no operation for a moment, covering [[solar cell]] exposure, or closing their [[lid]]). [[Crank (mechanism)|Crank]]-powered calculators were also common in the early computer era.

===Key layout===
The following keys are common to most pocket calculators.  While the arrangement of the digits is standard, the positions of other keys vary from model to model; the illustration is an example.
{| class="wikitable" style="clear:right"
|+ Calculator buttons and their meanings
|-
| MC or CM || '''M'''emory '''C'''lear
| rowspan="15" |{{Calculator layout|float=center}}
|-
| MR, RM, or MRC || '''M'''emory '''R'''ecall
|-
| M− || '''M'''emory '''Subtraction'''
|-
| M+ || '''M'''emory '''Addition'''
|-
| C or AC || '''A'''ll '''C'''lear
|-
| CE || '''C'''lear (last) '''E'''ntry; sometimes called CE/C: a first press clears the last entry (CE), a second press clears all (C)
|-
| ± or CHS || Toggle positive/negative number aka '''CH'''ange '''S'''ign
|-
| % || [[Percent]]
|-
| ÷ || [[Division (mathematics)|Division]]
|-
| × || [[Multiplication]]
|-
| − || [[Subtraction]]
|-
| + || [[Addition]]
|-
| . || [[Decimal point]]
|-
| √ || [[Square root]]
|-
| = || Result
|}

The arrangement of digits on calculator and other [[numeric keypad]]s with the {{key press|7}}-{{key press|8}}-{{key press|9}} keys two rows above the {{key press|1}}-{{key press|2}}-{{key press|3}} keys is  derived from calculators and [[cash register]]s. It is notably different from the layout of [[Telephone keypad|telephone Touch-Tone keypads]] which have the {{key press|1}}-{{key press|2}}-{{key press|3}} keys on top and {{key press|7}}-{{key press|8}}-{{key press|9}} keys on the third row.